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Hydronephrosis in Renal Ectopia: Incidence, Etiology and Significance
0022-5347 /94/1516-1660$03.00/0 THE JOURNAL OF UROLOGY Copyright© 1994 by AMERICAN UROLOGICAL ASSOCIATION, INC.
Vol. 151, 1660-1661, June 1994 Printed in U.S.A.
HYDRONEPHROSIS IN RENAL ECTOPIA: INCIDENCE, ETIOLOGY AND SIGNIFICANCE PHILIP E. GLEASON, PANAYOTIS P. KELALIS, DOUGLAS A. HUSMANN STEPHEN A. KRAMER*
AND
From the Department of Urology, Mayo Clinic and Mayo Foundation, Rochester, Minnesota, and Mayo Clinic Jacksonville, Jacksonville, Florida
ABSTRACT
The incidence, cause and significance of hydronephrosis in patients with renal ectopia are unknown. Therefore, we conducted a retrospective review of 77 patients with 82 ectopic kidneys. Of 82 kidneys 46 (56%) had hydronephrosis. Dilatation of the renal pelvis was the result of primary ureteropelvic or ureterovesical obstruction in 52%, grade 3, 4 or 5 vesicoureteral reflux in 26% and extrarenal collecting systems with malrotation that produced apparent ureteropelvic junction obstruction in 22%. Surgery was performed in 41 patients, including primary nephrectomy in 18, ureteral reimplantation in 14 and ureteropelvic junction repair in 8. Hydronephrosis was present in 15 of 58 contralateral nonectopic kidneys, and 11 required surgery mostly for vesicoureteral reflux. Solitary ectopic kidneys with no associated obstruction or reflux demonstrated normal renal function. Our data indicate that the prognosis in renal ectopia relates directly to the associated urological disease and timely surgical intervention, not to ectopia alone. KEY WORDS: hydronephrosis, choristoma, kidney
Renal ectopia describes a kidney that lies outside the renal fossa. Failure of the kidney to complete ascent can be due to an abnormality of the ureteral bud, metanephric blastema, genetic abnormalities, teratogenic causes or anomalous vasculature acting as a barrier to ascent. 1 Simple renal ectopia refers to a kidney that remains in the ipsilateral retroperitoneal space. The most common position is in the pelvis opposite the sacrum and below the aortic bifurcation. Crossed renal ectopia, which refers to a kidney that crosses the midline, may be associated with fusion to the contralateral kidney. Renal ectopia has been reported in approximately 1 in 1,000 autopsies. Screening studies demonstrate the incidence of ectopic kidney to be 1 in 5,000 patients but clinical recognition is estimated to be only 1 in 10,000. 2- 4 Because of its rarity and often vague or atypical symptoms, renal ectopia is commonly an unsuspected finding that is diagnosed during radiographic evaluation of the genitourinary or gastrointestinal systems, or during examination of children with multiple congenital anomalies. 5 • 6 The urologist then has the responsibility to determine if ectopia is symptomatic or otherwise medically significant. In addition, interpretation of the radiographic evaluation can be confusing because of malrotation, decreased renal function, overlying bony densities and associated congenital anomalies. 5 Ectopic kidneys are known to be associated with an increased incidence of renal and other organ system disease. 7 Therefore, although hydronephrosis is the most common significant finding in renal ectopia, its relationship to renal function in such cases is unknown. 8 We evaluate the incidence, cause and significance of hydronephrosis in renal ectopia in a large group of patients.
excretory urography (IVP). Whether hydronephrosis was present in the ectopic kidney and the nonectopic contralateral kidney was evaluated. Associated pathological findings were recorded, including malrotation, obstruction and vesicoureteral reflux. Obstructive uropathy at either the ureteropelvic junction or the ureterovesical junction was diagnosed by IVP, radioisotopic diethylenetriaminepentaacetic acid scanning, and occasional antegrade or retrograde pyelography. Renal function was assessed by serum creatinine and urea levels, and by radioisotopic renal scans. Operative procedures and the results of longterm followup were noted. RESULTS
In 41 male and 36 female patients 82 ectopic kidneys were identified. Average patient age at presentation was 9.8 years (range 1 day to 39 years). All but 4 patients were younger than 18 years and none of them required surgery. The clinical presentations are summarized in table 1. Left renal ectopia was present in 42 kidneys (51%), right ectopia in 30 (37%) and bilateral ectopia in 10 (12%). The most common locations of the ectopic kidney were pelvic (45 kidneys, 55 %) and cross fused (22, 27%). There were 10 lumbar kidneys (12%), 4 crossed nonfused (5 %) and 1 thoracic (1 %) . A solitary ectopic kidney was present in 14 patients (17%). Nonrenal systemic diseases existed in 40 patients (52%) (table 2). The organ systems most commonly involved were the musculoskeletal and genitourinary (nonrenal anomalies). Most patients with associated disease had multiple system involvement. TABLE 1.
Presenting symptoms and signs in ectopia
77 patients
with renal
MATERIALS AND METHODS
Presentation
No. Complaints*
% Pts.
The charts of 77 consecutive patients with renal ectopia who were seen at the Mayo Clinic during the last 70 years were reviewed. Patients with horseshoe kidney were excluded. Clinical presentation, ectopic position of the renal unit or units, and associated genitourinary and other systemic diseases were noted. Hydronephrosis was defined as dilatation of the pelvicaliceal system that was documented on ultrasonography or
Urinary tract infection Gastrointestinal evaluation for abdominal pain Palpable mass Multiple congenital anomalies Hematuria Incontinence Renal insufficiency Hypertension Chest mass on radiography Nephrolithiasis
34 18
44 23
15 15 5
19 19 6 5 3 3 1 1
Accepted for publication November 19, 1993. * Requests for reprints: Department of Urology, Mayo Clinic, 200 First St., S.W., Rochester, Minnesota 55905. 1660
4
2 2 1 1
* Some patients had more than 1 symptom or sign at presentation.
1661
HYDRONEPHROSIS IN RENAL ECTOPIA TABLE 2. Associated organ system disease in 77 patients No. Pts. (%)*
Examples
Musculoskeletal
20 (26)
Genitourinary
20 (26)
Cardiovascular
8 (10)
Gastrointestinal
7 (9)
Pulmonary Neurological
1 (1) 1 (1)
Vertebral; sacral agenesis, cleft palate Absent vagina, hypospadias, undescended testis Tetralogy of Fallot, patent ductus arteriosus, ventricular septa! defect, aortic coarctation Imperforate anus, cloaca! anomaly, Bochdalek's hernia Hypoplastic lung In utero hemorrhage
Organ System
* Some patients had involvement of more than 1 organ system.
Of the 82 ectopic kidneys 46 (56%) had hydronephrosis, including 24 (52%) with obstruction. The site of obstruction was the ureteropelvic junction in 17 kidneys, of which 13 had primary and 4 secondary obstruction associated with high grade vesicoureteral reflux. Obstruction at the ureterovesical junction occurred in 7 kidneys, including 5 with a primary obstructing megaureter and 2 with an ectopic and obstructive megaureter. Grades 3 to 5 vesicoureteral reflux caused hydronephrosis in 12 ectopic kidneys (26%). Large extrarenal pelves and calices were associated with malrotation alone in 10 (22%) hydronephrotic ectopic kidneys, in which radiographic studies revealed no evidence of obstruction or vesicoureteral reflux. Of 58 contralateral nonectopic kidneys hydronephrosis was demonstrated in 15, the cause of which was obstruction in 5 (33%), grades 3 to 5 vesicoureteral reflux in 9 (60%) and malrotation and hydronephrosis without obstruction or vesicoureteral reflux in 1 (7%). Surgery was performed in 44 of the 82 ectopic kidneys (54 %). The most common procedure was primary nephrectomy (18 kidneys) for a nonfunctioning renal unit with associated disease, such as chronic pyelonephritis, vesicoureteral reflux or obstruction. Ureteral reimplantation was performed in 14 patients for high grade reflux with or without associated ureteropelvic junction obstruction. Primary dismembered pyeloplasty was done in 4 kidneys and ureterocalicostomy in 4. Of 58 nonectopic contralateral kidneys 11 (19%) also required surgery, most commonly ureteral reimplantation for vesicoureteral reflux. At initial evaluation 25 ectopic kidneys had diminished renal function determined by serum creatinine concentration or radioisotopic renal scans. Only 7 of these 25 kidneys (28%) demonstrated resumption of renal growth and improvement in function documented by radioisotopic renal scans after successful renal sparing procedures, such as ureteral reimplantation and pyeloplasty. The remaining 18 kidneys required nephrectomy for diminished function. Interestingly, of 11 patients with normally functioning solitary ectopic kidneys none had vesicoureteral reflux or ureteropelvic junction obstruction. At a mean followup of 8 years (range 1 to 27) all 11 had normal renal function. DISCUSSION
The primary goal of our study was to evaluate the incidence, cause and significance of hydronephrosis in patients with ectopic kidneys. Whereas the overall incidence of hydronephrosis is 0.2% in general screening studies,3 we noted a 56% incidence of hydronephrosis in ectopic kidneys and 26% in nonectopic
contralateral kidneys. Dilatation of the ectopic renal pelvis was the result of ureteropelvic junction obstruction in 37% of the cases, ureterovesical junction obstruction in 15%, vesicoureteral reflux in 26% or extrarenal pelves and calices with renal malrotation in 22%. Obstructive uropathy was often silent, with resultant loss of renal parenchyma and decreased renal function as manifested by the 25 kidneys that showed diminished renal function on initial evaluation. Vesicoureteral reflux accounted for hydronephrosis in 26% of ectopic kidneys and was the most common source of hydronephrosis in 60% of contralateral kidneys. In children with concomitant vesicoureteral reflux and ureteropelvic junction obstruction the surgical approach depends on the degree of reflux and the extent of obstruction. Pyeloplasty is the first procedure in cases of definite obstruction and low grade reflux. 9 In children who have equivocal ureteropelvic junction obstruction and significant vesicoureteral reflux ureteral reimplantation is performed initially, and followup consists of IVP and renal scans. 9 The abnormal position and malrotation of the ectopic kidney resulted in nonobstructed nonrefluxing hydronephrosis in 22% of ectopic kidneys. These abnormal pyelocaliceal patterns must be differentiated from true ureteropelvic junction obstruction, since dilatation is not the result of obstruction and does not require surgery. This condition is best evaluated by either a radioisotopic furosemide renal scan or an antegrade perfusion study. Our population is based primarily on symptomatic presentation. However, several recent cases have been identified on screening evaluation alone. Hydronephrosis is a serious but nonspecific and often silent predictor of associated disease in patients with renal ectopia. This observation, when combined with the 19% incidence of required surgical intervention in the contralateral nonectopic kidney, emphasizes the need for complete urological evaluation. The prognosis for preservation of renal function is directly related to timely surgical intervention and the associated urological disease, for example obstruction or vesicoureteral reflux, of the ectopic and contralateral kidney, not to renal ectopia alone. REFERENCES
1. Malek, R. S., Kelalis, P. P. and Burke, E. C.: Ectopic kidney in children and frequency of association with other malformations. Mayo Clin. Proc., 46: 461, 1971. 2. Abeshouse, B. S. and Bhisitkul, I.: Crossed renal ectopia with and without fusion. Urol. Int., 9: 63, 1959. 3. Sheih, C. P., Liu, M. B., Hung, C. S.,Xang, K. H., Chen, W. Y. and Lin, C. Y.: Renal abnormalities in school children. Pediatrics, 84: 1086, 1989. 4. Thompson, G. J. and Pace, J.M.: Ectopic kidney: a review of 97 cases. Surg., Gynec. & Obst., 64: 935, 1937. 5. Donahoe, P. K. and Hendren, W. H.: Pelvic kidney in infants and children: experience with 16 cases. J. Ped. Surg., 15: 486, 1980. 6. Anderson, E. E. and Harrison, J. H.: Surgical importance of the solitary kidney. New Engl. J. Med., 273: 683, 1965. 7. Kelalis, P. P., Malek, R. S. and Segura, J. W.: Observations on renal ectopia and fusion in children. J. Urol., 110: 588, 1973. 8. Downs, R. A., Lane, J. W. and Burns, E.: Solitary pelvic kidney: its clinical implications. Urology, 1: 51, 1973. 9. Hollowell, J. G., Altman, H. G., Snyder, H. McC., III and Duckett, J. W.: Coexisting ureteropelvic junction obstruction and vesicoureteral reflux: diagnostic and therapeutic implications. J. Urol., 142: 490, 1989.
Vol. 151, 1660-1661, June 1994 Printed in U.S.A.
HYDRONEPHROSIS IN RENAL ECTOPIA: INCIDENCE, ETIOLOGY AND SIGNIFICANCE PHILIP E. GLEASON, PANAYOTIS P. KELALIS, DOUGLAS A. HUSMANN STEPHEN A. KRAMER*
AND
From the Department of Urology, Mayo Clinic and Mayo Foundation, Rochester, Minnesota, and Mayo Clinic Jacksonville, Jacksonville, Florida
ABSTRACT
The incidence, cause and significance of hydronephrosis in patients with renal ectopia are unknown. Therefore, we conducted a retrospective review of 77 patients with 82 ectopic kidneys. Of 82 kidneys 46 (56%) had hydronephrosis. Dilatation of the renal pelvis was the result of primary ureteropelvic or ureterovesical obstruction in 52%, grade 3, 4 or 5 vesicoureteral reflux in 26% and extrarenal collecting systems with malrotation that produced apparent ureteropelvic junction obstruction in 22%. Surgery was performed in 41 patients, including primary nephrectomy in 18, ureteral reimplantation in 14 and ureteropelvic junction repair in 8. Hydronephrosis was present in 15 of 58 contralateral nonectopic kidneys, and 11 required surgery mostly for vesicoureteral reflux. Solitary ectopic kidneys with no associated obstruction or reflux demonstrated normal renal function. Our data indicate that the prognosis in renal ectopia relates directly to the associated urological disease and timely surgical intervention, not to ectopia alone. KEY WORDS: hydronephrosis, choristoma, kidney
Renal ectopia describes a kidney that lies outside the renal fossa. Failure of the kidney to complete ascent can be due to an abnormality of the ureteral bud, metanephric blastema, genetic abnormalities, teratogenic causes or anomalous vasculature acting as a barrier to ascent. 1 Simple renal ectopia refers to a kidney that remains in the ipsilateral retroperitoneal space. The most common position is in the pelvis opposite the sacrum and below the aortic bifurcation. Crossed renal ectopia, which refers to a kidney that crosses the midline, may be associated with fusion to the contralateral kidney. Renal ectopia has been reported in approximately 1 in 1,000 autopsies. Screening studies demonstrate the incidence of ectopic kidney to be 1 in 5,000 patients but clinical recognition is estimated to be only 1 in 10,000. 2- 4 Because of its rarity and often vague or atypical symptoms, renal ectopia is commonly an unsuspected finding that is diagnosed during radiographic evaluation of the genitourinary or gastrointestinal systems, or during examination of children with multiple congenital anomalies. 5 • 6 The urologist then has the responsibility to determine if ectopia is symptomatic or otherwise medically significant. In addition, interpretation of the radiographic evaluation can be confusing because of malrotation, decreased renal function, overlying bony densities and associated congenital anomalies. 5 Ectopic kidneys are known to be associated with an increased incidence of renal and other organ system disease. 7 Therefore, although hydronephrosis is the most common significant finding in renal ectopia, its relationship to renal function in such cases is unknown. 8 We evaluate the incidence, cause and significance of hydronephrosis in renal ectopia in a large group of patients.
excretory urography (IVP). Whether hydronephrosis was present in the ectopic kidney and the nonectopic contralateral kidney was evaluated. Associated pathological findings were recorded, including malrotation, obstruction and vesicoureteral reflux. Obstructive uropathy at either the ureteropelvic junction or the ureterovesical junction was diagnosed by IVP, radioisotopic diethylenetriaminepentaacetic acid scanning, and occasional antegrade or retrograde pyelography. Renal function was assessed by serum creatinine and urea levels, and by radioisotopic renal scans. Operative procedures and the results of longterm followup were noted. RESULTS
In 41 male and 36 female patients 82 ectopic kidneys were identified. Average patient age at presentation was 9.8 years (range 1 day to 39 years). All but 4 patients were younger than 18 years and none of them required surgery. The clinical presentations are summarized in table 1. Left renal ectopia was present in 42 kidneys (51%), right ectopia in 30 (37%) and bilateral ectopia in 10 (12%). The most common locations of the ectopic kidney were pelvic (45 kidneys, 55 %) and cross fused (22, 27%). There were 10 lumbar kidneys (12%), 4 crossed nonfused (5 %) and 1 thoracic (1 %) . A solitary ectopic kidney was present in 14 patients (17%). Nonrenal systemic diseases existed in 40 patients (52%) (table 2). The organ systems most commonly involved were the musculoskeletal and genitourinary (nonrenal anomalies). Most patients with associated disease had multiple system involvement. TABLE 1.
Presenting symptoms and signs in ectopia
77 patients
with renal
MATERIALS AND METHODS
Presentation
No. Complaints*
% Pts.
The charts of 77 consecutive patients with renal ectopia who were seen at the Mayo Clinic during the last 70 years were reviewed. Patients with horseshoe kidney were excluded. Clinical presentation, ectopic position of the renal unit or units, and associated genitourinary and other systemic diseases were noted. Hydronephrosis was defined as dilatation of the pelvicaliceal system that was documented on ultrasonography or
Urinary tract infection Gastrointestinal evaluation for abdominal pain Palpable mass Multiple congenital anomalies Hematuria Incontinence Renal insufficiency Hypertension Chest mass on radiography Nephrolithiasis
34 18
44 23
15 15 5
19 19 6 5 3 3 1 1
Accepted for publication November 19, 1993. * Requests for reprints: Department of Urology, Mayo Clinic, 200 First St., S.W., Rochester, Minnesota 55905. 1660
4
2 2 1 1
* Some patients had more than 1 symptom or sign at presentation.
1661
HYDRONEPHROSIS IN RENAL ECTOPIA TABLE 2. Associated organ system disease in 77 patients No. Pts. (%)*
Examples
Musculoskeletal
20 (26)
Genitourinary
20 (26)
Cardiovascular
8 (10)
Gastrointestinal
7 (9)
Pulmonary Neurological
1 (1) 1 (1)
Vertebral; sacral agenesis, cleft palate Absent vagina, hypospadias, undescended testis Tetralogy of Fallot, patent ductus arteriosus, ventricular septa! defect, aortic coarctation Imperforate anus, cloaca! anomaly, Bochdalek's hernia Hypoplastic lung In utero hemorrhage
Organ System
* Some patients had involvement of more than 1 organ system.
Of the 82 ectopic kidneys 46 (56%) had hydronephrosis, including 24 (52%) with obstruction. The site of obstruction was the ureteropelvic junction in 17 kidneys, of which 13 had primary and 4 secondary obstruction associated with high grade vesicoureteral reflux. Obstruction at the ureterovesical junction occurred in 7 kidneys, including 5 with a primary obstructing megaureter and 2 with an ectopic and obstructive megaureter. Grades 3 to 5 vesicoureteral reflux caused hydronephrosis in 12 ectopic kidneys (26%). Large extrarenal pelves and calices were associated with malrotation alone in 10 (22%) hydronephrotic ectopic kidneys, in which radiographic studies revealed no evidence of obstruction or vesicoureteral reflux. Of 58 contralateral nonectopic kidneys hydronephrosis was demonstrated in 15, the cause of which was obstruction in 5 (33%), grades 3 to 5 vesicoureteral reflux in 9 (60%) and malrotation and hydronephrosis without obstruction or vesicoureteral reflux in 1 (7%). Surgery was performed in 44 of the 82 ectopic kidneys (54 %). The most common procedure was primary nephrectomy (18 kidneys) for a nonfunctioning renal unit with associated disease, such as chronic pyelonephritis, vesicoureteral reflux or obstruction. Ureteral reimplantation was performed in 14 patients for high grade reflux with or without associated ureteropelvic junction obstruction. Primary dismembered pyeloplasty was done in 4 kidneys and ureterocalicostomy in 4. Of 58 nonectopic contralateral kidneys 11 (19%) also required surgery, most commonly ureteral reimplantation for vesicoureteral reflux. At initial evaluation 25 ectopic kidneys had diminished renal function determined by serum creatinine concentration or radioisotopic renal scans. Only 7 of these 25 kidneys (28%) demonstrated resumption of renal growth and improvement in function documented by radioisotopic renal scans after successful renal sparing procedures, such as ureteral reimplantation and pyeloplasty. The remaining 18 kidneys required nephrectomy for diminished function. Interestingly, of 11 patients with normally functioning solitary ectopic kidneys none had vesicoureteral reflux or ureteropelvic junction obstruction. At a mean followup of 8 years (range 1 to 27) all 11 had normal renal function. DISCUSSION
The primary goal of our study was to evaluate the incidence, cause and significance of hydronephrosis in patients with ectopic kidneys. Whereas the overall incidence of hydronephrosis is 0.2% in general screening studies,3 we noted a 56% incidence of hydronephrosis in ectopic kidneys and 26% in nonectopic
contralateral kidneys. Dilatation of the ectopic renal pelvis was the result of ureteropelvic junction obstruction in 37% of the cases, ureterovesical junction obstruction in 15%, vesicoureteral reflux in 26% or extrarenal pelves and calices with renal malrotation in 22%. Obstructive uropathy was often silent, with resultant loss of renal parenchyma and decreased renal function as manifested by the 25 kidneys that showed diminished renal function on initial evaluation. Vesicoureteral reflux accounted for hydronephrosis in 26% of ectopic kidneys and was the most common source of hydronephrosis in 60% of contralateral kidneys. In children with concomitant vesicoureteral reflux and ureteropelvic junction obstruction the surgical approach depends on the degree of reflux and the extent of obstruction. Pyeloplasty is the first procedure in cases of definite obstruction and low grade reflux. 9 In children who have equivocal ureteropelvic junction obstruction and significant vesicoureteral reflux ureteral reimplantation is performed initially, and followup consists of IVP and renal scans. 9 The abnormal position and malrotation of the ectopic kidney resulted in nonobstructed nonrefluxing hydronephrosis in 22% of ectopic kidneys. These abnormal pyelocaliceal patterns must be differentiated from true ureteropelvic junction obstruction, since dilatation is not the result of obstruction and does not require surgery. This condition is best evaluated by either a radioisotopic furosemide renal scan or an antegrade perfusion study. Our population is based primarily on symptomatic presentation. However, several recent cases have been identified on screening evaluation alone. Hydronephrosis is a serious but nonspecific and often silent predictor of associated disease in patients with renal ectopia. This observation, when combined with the 19% incidence of required surgical intervention in the contralateral nonectopic kidney, emphasizes the need for complete urological evaluation. The prognosis for preservation of renal function is directly related to timely surgical intervention and the associated urological disease, for example obstruction or vesicoureteral reflux, of the ectopic and contralateral kidney, not to renal ectopia alone. REFERENCES
1. Malek, R. S., Kelalis, P. P. and Burke, E. C.: Ectopic kidney in children and frequency of association with other malformations. Mayo Clin. Proc., 46: 461, 1971. 2. Abeshouse, B. S. and Bhisitkul, I.: Crossed renal ectopia with and without fusion. Urol. Int., 9: 63, 1959. 3. Sheih, C. P., Liu, M. B., Hung, C. S.,Xang, K. H., Chen, W. Y. and Lin, C. Y.: Renal abnormalities in school children. Pediatrics, 84: 1086, 1989. 4. Thompson, G. J. and Pace, J.M.: Ectopic kidney: a review of 97 cases. Surg., Gynec. & Obst., 64: 935, 1937. 5. Donahoe, P. K. and Hendren, W. H.: Pelvic kidney in infants and children: experience with 16 cases. J. Ped. Surg., 15: 486, 1980. 6. Anderson, E. E. and Harrison, J. H.: Surgical importance of the solitary kidney. New Engl. J. Med., 273: 683, 1965. 7. Kelalis, P. P., Malek, R. S. and Segura, J. W.: Observations on renal ectopia and fusion in children. J. Urol., 110: 588, 1973. 8. Downs, R. A., Lane, J. W. and Burns, E.: Solitary pelvic kidney: its clinical implications. Urology, 1: 51, 1973. 9. Hollowell, J. G., Altman, H. G., Snyder, H. McC., III and Duckett, J. W.: Coexisting ureteropelvic junction obstruction and vesicoureteral reflux: diagnostic and therapeutic implications. J. Urol., 142: 490, 1989.